Grinding wheel truing device for grinding machines, more especially for thread grinding machines



y 1949. F. TURRETTINI 2,475,210

GRINDING WHEEL TRUING DEVICE FOR GRINDING MACHINES MORE ESPECIALLY FOR THREAD GRINDING MACHINES 2 Sheets-Sheet 1 Filed Oct. 22. 1947 52 a0 33 22 a1 29 25 Q 34 2 36 In ve/fior f. Frnand Erreff/m' A ri /"n y July 5, 1949. F TURRETTINI 2,475,210

GRINDING WHEEL TRUING DEVICE FOR GRINDING MACHINES MORE ESPECIALLY FOR THREAD GRINDING MACHINES 2 Sheets-Sheet 2.

Filed Oct. 22, 1.947

m yen/or A 770/)? e y Patented July 5, 1949 GRINDING WHEEL TRUING DEVICE FOR GRINDING MACHINES, MORE ESPE- CIALLY FOR THREAD GRINDING MA- CHIN ES Fernand Turrettini, Bellevue-Geneva, Switzerland, assignor to Societe Genevoise dInstruments de Physique, Geneva, Switzerland, a firm of Switzerland Application October 22, 1947, Serial No. 781,458 In Switzerland November 13, 1946 Claims. 1

The object of the present invention is a grinding wheel truing device for grinding machine, more especially for a thread grinding machine.

Numerous devices serving this purpose are known. Some of them are based on the principle of a cam of suitable shape imparting to 2. diamond point a reciprocating movement perpendicular to the axis of the work piece, this reciprocating movement being synchronised with a continuous translation movement of the diamond in a direction parallel to said axis, in such a way that, by the combination of these two movements, the diamond point describes the required profile on the active edge of the grinding wheel.

This system has the drawback that the operation of the shape of the diamond point, as an effect of the natural wear, modifies rapidly the profile obtained on the grinding wheel.

Other truing apparatuses comprise a stationary device provided with a diamond following a path parallel to the flanks of the grinding wheel edge, this movement being completed by a pivoting movement about an axis approximately tangent to the grinding wheel edge, in such a way that the diamond, after having trued one flank, passes on to the other flank by following the are of "circle connecting the two flanks of the grinding wheel. This system has the drawback that it is very difiicult to adjust the pivoting angle of the device for obtaining an accurate profile angle on the grinding wheel.

There are also truing devices comprising two movable diamond-holder slides, forming between them a set or adjustable angle, and which are operated by a common control member; the diamonds true alternately the faces of the grinding wheel in opposite direction. The adjustment of the angular position of the slides to obtain the correct angle of the grinding wheel profile, is realised in these systems by means of very complicated and not over-precise mechanisms.

The device according to the invention avoids the drawbacks involved in the known systems. It is characterized by two diamond-holder slides movable perpendicularly to the axis of the work piece, on a common carriage, one of said slides presenting a solid wedge bearing on a roller whose shaft is mounted at right angle on a guideway on which said carriage is slidable in a direction parallel to the axis of the work piece, said slides being operatively connected to a common swinging control member for reciprocating movement in opposite direction to one another, whereby the carriage receives a movement on its guideway in synchronism with that of the slides, and 'at right angle thereto, the angle of the wedge being half that which is formed between the flanks of the grinding wheel, the whole operating in such a way that the two diamonds cut simultaneously both flanks of the grinding wheel under the action of the reciprocating movement imparted to the control member.

The device according to the invention has thus the advantages that both flanks of the grinding wheel are cut simultaneously, that the diamonds always attack the grinding wheel by the same spot of their point, and that the angle to be formed between the flanks of the grinding wheel is determined by the angle of the wedge, which is a mechanical. part of simple shape, which it is easy to manufacture with precision. This wedge can be mounted removably, in order to allow truing a grinding wheel at for the SI profile, and then to pass to the Acme profile, simply by replacing the 30 wedge, by a 15 one.

The attached drawing represents by way of example an embodiment of the present invention.

Fig. 1 is a plan view thereof.

Figs. 2, 3 and 4 are cross-sections along IIII, 1II-III and IVIV of Fig. 1.

On the drawing, and especially in Fig. 1, I shows the grinding wheel, 2 and 3 its two flanks, 4 and 5 the cutting diamonds operating respectively on these flanks, 6 and I the setting of these diamonds, while 8 and 9 show their mounting on the slides It and l I, these slides are provided with racks l2 and I3 meshing with a pinion M for imparting to the slides a reciprocating movement in opposite direction to one another; I5 is the shaft of this pinion.

The wedge It, the angle of which determines half the angle comprised between the flanks of the grinding wheel, is secured on the slide It] by means of screws ll and I8. The oblique side of the wedge bears on a roller ll pivoted at l8. A tightly sealed casing l9 surrounds the whole device. Apertures 68 and 69 are provided in the casing for letting out the end of the slides l0 and l l with their mountings 8 and 9.

Fig. 2 shows how the slide H) can move on the face 26) of a guideway 2| secured by screws 22 and 23 on the carriage 21. To the right and to the left of the part of the guideway 2| by which it is secured on the carriage 21, this guideway comprises extensions 24 and 24', of reduced thickness, the inner surfaces 28 and 283' of which cooperate with retaining plates 25 and 26 in preventing the slide I!) from being lifted. These retaining plates are secured on the lower face of the slide 10.

The carriage 2! is movable on the guideway 29, on which it is guided by its faces 30, 3| and 32, which fit on the corresponding faces of the guideway 29. Retaining plates 35 and 36, secured on thecarriage' 2,1, cooperate with the faces 33 and 34 of" the guideway 29.

Fig. 3 shows that the slide ll is mounted substantially in the same way as the slide It). In addition to the parts already described, one notices that the wedge 16 is sets in aqgroove 31, in order to define accuratelyits :position, and that the guideway 2| and 2| are also secured by means of screws 39 and 39 in,grooves38, and.38' formed in the carriage 21, thusensuring the parallelism of the guideways.

Furthermore the pivot 18' of the roller I1 is shown being part of a shaft. 48 secured. at 40 on the guideway 29 by means of screws 4 I, and the carriage 21 is guided on the guideway 29 by means of retaining plates 42 and 43 secured. on the carriage 21 by means of screws 44.

Furthena spring 45, hearing on the one hand onthe bottom ,of a recess 46 formed in the guide- Way 29 and on the ,other hand on a part 41 of thecarriage assembly 21, tends to push the latter to the right, to make; sure that the roller ll bears the dge 16. The? shaft.48, secured on the guideway 29 and carrying the roller ll, traverses the carriage. 21 through an aperture 49 which is large enoughto-allow for the movement of the carriage 2'! on. the guideway 29.

The guideway 29.is secured on a base 50 by means of thescrews and 5|; a plate 52 is interposed between 29 and-50 to meet the retaining plates. 42 and.43, ,35. and 36.

The lowersurface53 of the base5ii is cylindrically shaped, in order to allow tilting of the apparatus on the frame 54, for truing on a grinding wheel, profiles contained, in a plane which is oblique .in respectwith the, axis of the grinding wheel. The base-.50 is, held on the frame 54 by means whicharenot shown on the drawing.

Fig- 4 shows, espeoialy the control member of the slides I 0 and II. Theshaft 15 of the pinion .14 is held in a bushingjfisecured by the screws for-limiting thepossible travel of the slides Ill and II under the action of the pinion. l4.

Theioperation ofthis apparatus is as follows: Upon actuation of the hand lever 58, the dia- .mondholderslides and II are moved in opposite-directions. The axial movement of the .slide 10, which carries the wedge l6 bearing against the immovable roller [4, causes the perp endicular:.movement of the carriage assembly -21,--wi-th all what it carries,in consequence of the obliquity of thewedge. The diamond 4 must follow an'oblique path parallel to the edge of the Wedge l6 while the ,diamond; 5, must follow a path in the-oppositedirection, symmetrically oblique in respect with-the plane of the grinding wheel.

-Bothdiamonds follow simultaneously both flanks of the grinding wheel in opposite direction to one another, and. theirgdirection of movement is re- .versed when the hand lever 58qis being brought back to its starting point after having reached the endof its-swing.

The. above described truing devicethus provides for the truing of. grinding wheels having .a triangular profile. -,-In several thread systems,

'4 and for instance in the Acme system, the top of the triangle is cut off by a, truncation. An additional diamond 62 enables carrying out this truncation on the grinding wheel. This diamond is borne by an arm 63 ended by a control handle v.64 and pivoted on a shaft 65 in a bearing 65 secured on the casing I9. An adjusting screw 61 is provided for setting the distance separating the truncation from the top of the triangle formed by said shaft, two diamond-holder slides slidable in said carriage at right angle to the direction of said guideway and operatively connected to a 'common swinging control member for reciprocating movements of said slides in opposite direction'toone another, a wedge secured on one of said slides and bearing by its oblique edge on said roller, and a spring operatively connected between said, guideway and said carriage and sup- :plying contact pressure between wedge and roller,

the angle of the .wedge being half that to be formed between the two directions of displace- .ment of both diamonds, whereby both diamonds out simultaneously both flanks of the grinding wheel under the action of a swinging movement .ing machine,;especially for a thread grinding -machine, a base secured on the machine frame,

a guideway secured on said base, a carriage slidable on said guideway, a slot in said carriage, a

shaft secured at right angle on said guideway and extending through'said slot, a roller pivoted on saidshaft, two diamond-holder slides slidable in said carriage atright angle to the directionof said guideway and operatively connected to a ,45'

common swinging control member for reciprocatfl n 'movement of said slides in opposite direction to; one another, a wedge secured on one of said ,slidesand'bearing by its oblique edge on said roller, and a spring operatively connected between said guideway and said carriage and supplying contact pressure between wedge and roller,

theangle of the wedge being half that to be .formed between the two directions of displacement of both diamonds, whereby both diamonds 'cut simultaneously both flanks of the grinding =wheel under the action of a swinging movement flanks of the grinding Wheel edge.

..3. In agrindingwheel truing device for grinding machine, especially for a thread grinding machine, a base secured on the machine frame,

a guideway secured on said base, a carriage slid- -able on said guideway, a slot in said carriage, a shaft secured at right angle on said guideway and extending through said slot, a roller pivoted on said shaft, two diamond-holder slides slidable in said carriage at right angle to the direction of said guidewa andoperatively connected toacom- ,-.mon swinging control member for reciprocating movements of said slides in opposite direction to one another, a wedge secured on one of said slides and bearing by its oblique edge on said roller, and a spring operatively connected between said guideway and said carriage and supplying contact pressure between wedge and roller, the angle of the wedge being half that to be formed between the two directions of displacement of both diamonds, whereby both diamonds out simultaneously both flanks of the grinding wheel under the action of a swinging movement given to the common control member, and a third diamond mounted on said carriage for alternating movement in a plane perpendicular to the bisector of said angle to be formed between said directions of displacement, for carrying out a truncation in the triangle formed by the two flanks of the grinding wheel edge.

4. In a grinding wheel truing device for grinding machine, especially for a thread grinding machine, a base secured on the machine frame, a guideway secured on said base, a carriage s1idable on said guideway, a slot in said carriage, a shaft secured at right angle on said guideway and extending through said slot, a roller pivoted on said shaft, two diamond-holder slides slidable in said carriage at right angle to the direction of said guideway and operatively connected to a common swinging control member for reciprocating movement of said slides in opposite direction to one another, a wedge secured on one of said slides and bearing by its oblique edge on said roller, and a spring operatively connected between said guideway and said carriage and supplying contact pressure between wedge and roller, the angle of the wedge being half that to be formed between the two directions of displacement of both diamonds, whereby both diamonds cut simultaneously both flanks of the grinding wheel under the action of a swinging movement given to the common control member, said wedge being mounted removably on its supporting slide.

5. In a grinding wheel truing device for grinding machine, especially for a thread grinding machine, a base secured on the machine frame, a guideway secured on said base, a carriage slidable on said guideway, a slot in said carriage, a first shaft secured at right angle on said guideway and extending through said slot, a roller pivoted on said first shaft, two diamond-holder slides slidable in said carriage at right angle to the direction of said guideway two racks secured on the diamond-holder slides respectively, a second shaft secured at right angle on said carriage, a pinion secured to said second shaft and meshing with both racks, a hand lever secured. to said second shaft, for reciprocating said slides in opposite direction to one another, a Wedge secured on one of said slides and bearing by its oblique edge on said roller, and a spring operatively connected between said guideway and said carriage for pressing said wedge against said roller, the angle of the wedge being half that to be formed between the two directions of the displacement of both diamonds whereby upon reciprocation of said hand lever both diamonds cut simultaneously both flanks of the grinding wheel.

FERNAND TURRE'I'IINI.

REFERENCES CITED The following referenlces are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,186,363 Candee et a1 Jan. 9, 1940 2,340,192 Locke Jan. 25, 1944 FOREIGN PATENTS Number Country Date 611,246 France July 3, 1926 

